ES2901603T3 - High silica AFX framework type zeolites - Google Patents

Abstract

An AFX framework type zeolite having, in its calcined form, a composition comprising the molar ratio: AI2O3:(n)SiO2 where n has a value of greater than 50 to 100.

Description

DESCRIPTION

High silica AFX framework type zeolites

Technical field of the invention

This description generally refers to an AFX framework type zeolite having a SiO 2 /AhO 3 molar ratio greater than 50 to 100, its synthesis and its use as an adsorbent and a catalyst.

Background of the invention

Both natural and synthetic molecular sieve materials (eg, zeolites, aluminophosphates, or mesoporous materials) have been shown to have catalytic properties for various types of hydrocarbon conversion and are used in various industrial processes. These materials are characterized by ordered porous crystal structures that can be determined by X-ray diffraction (XRD). Because the pores of these materials are of molecular dimensions, exclusive size selective adsorption is possible, hence the name "molecular sieves".

Molecular sieves are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Zeolite Nomenclature Commission. Under this classification, framework-type zeolites and other crystalline microporous molecular sieves, for which a structure has been established, are given a three-letter code and are described in the Atlas of Zeolite Framework Types, Sixth Revised Edition, Elsevier, 2007. Molecular sieves identified by the International Zeolite Association are known to have the AFX structure type. An example of an AFX framework type material is zeolite SSZ-16.

United States Patent No. 4,508,837 describes zeolite SSZ-16 and its preparation in the presence of a nitrogen-containing organic compound derived from 1,4-di(1-azoniabicyclo[2.2.2]octane) lower alkanes, wherein the moiety The lower alkane of the nitrogen-containing organic compound has 3 to 5 carbon atoms.

United States Patent No. 5,194,235 describes a method for preparing zeolite SSZ-16 using an organic structure directing agent DABCO-G-diquat where n is 3, 4 or 5. The prepared zeolite SSZ-16 is reported to have a SiO2/AhO3 molar ratio which is typically in a range from 8 to 15.

RF Lobo et al (Chem. Mater. 1996, 8, 2409-2411) report that zeolite SSZ-16 can only be synthesized in a restricted range of SiO2/AhO3 molar ratios.

United States Patent No. 8,562,942 describes the synthesis of an AFX framework-type zeolite in the presence of 1,3-bis(1-adamantyl)imidazolium cations in a SiO2/AhO3 molar ratio of 35 and a hydroxide/silica molar ratio of 0.05 for the reaction mixture. At higher SiO 2 /AhO 3 molar ratios (eg, 50 or 100), materials other than zeolites of the AFX framework type were produced.

United States Patent Application Publication No. 2016/0137518 describes an aluminosilicate zeolite having at least 90% phase-pure AFX structure and a SiO2/AhO3 molar ratio of 12 to 50.

In accordance with the present disclosure, an aluminosilicate zeolite AFX having an SiO2/AI2O3 molar ratio greater than 50 to 100 is disclosed.

Short description

The present invention provides an AFX type zeolite as set forth in claim 1, a method as set forth in claim 7 and a process as set forth in claims 9 and 10.

In one aspect, an AFX framework type zeolite is provided having, in its calcined form, a SiO2/AI2O3 molar ratio of greater than 50 to 100.

In another aspect, an AFX framework type zeolite is provided having, in its anhydrous, synthesized form, a composition, in terms of molar ratios, as follows:

where Q comprises 1,3-bis(1-adamantyl)imidazolium cations and M is a metal selected from Groups 1 and 2 of the Periodic Table.

In a further aspect, there is provided a method of synthesizing an AFX framework type zeolite having a SiÜ2/AhO3 molar ratio greater than 50 to 100, the method comprising: (a) providing a reaction mixture comprising: (1) a aluminum source comprising a FAU framework type zeolite; (2) a separate source of silicon; (3) a source of at least one metal (M) selected from Groups 1 and 2 of the Periodic Table; (4) a 1,3-bis(l-adamantyl) imidazolium cation source (Q); (5) hydroxide ions; and (6) water; and (b) subjecting the reaction mixture to crystallization conditions sufficient to form frame-type zeolite crystals AFX, wherein the reaction mixture has a composition, in terms of molar proportions, as follows:

In yet another aspect, there is provided a process for converting a feedstock comprising an organic compound to a conversion product comprising the step of contacting the feedstock with a catalyst under organic compound conversion conditions, the catalyst comprising an active form of the present frame-type zeolite AFX.

In yet another aspect, a process for selectively reducing nitrogen oxides (NOx) is provided, the process comprising contacting a NOx-containing gas stream with a catalyst comprising an active form of the present framework-type zeolite AFX.

Description of Exemplary Embodiments

Introduction

The following terms will be used throughout the specification and shall have the following meanings unless otherwise indicated.

The term "zeolite" refers to crystalline aluminosilicate compositions that are microporous and that are formed from corner-sharing AIO2 and SiÜ2 tetrahedra.

The terms "framework type" are used in the sense described in "Atlas of Zeolite Framework Types", Sixth Revised Edition, Elsevier, 2007.

The term "as synthesized" is used herein to refer to a zeolite in its form after crystallization, prior to removal of the organic structure directing agent. The term "anhydrous" is used herein to refer to a zeolite substantially devoid of adsorbed water either physically or chemically.

As used herein, the numbering scheme for periodic table groups is as described in Chem. Eng. News, 63(5), 27 (1985).

Reaction mixture

In general, the present framework-type zeolite AFX is prepared by: (a) providing a reaction mixture comprising: (1) an aluminum source comprising a framework-type zeolite FAU; (2) a separate source of silicon; (3) a source of at least one metal (M) selected from Groups 1 and 2 of the Periodic Table; (4) a 1,3-bis(1-adamantyl) imidazolium cation source (Q); (5) hydroxide ions; and (6) water; and (b) subjecting the reaction mixture to crystallization conditions sufficient to form frame-type zeolite AFX crystals.

The composition of the reaction mixture from which the AFX framework-type zeolite is formed, in terms of molar ratios, is identified in Table 1 below:

wherein the composition variables M and Q are as described earlier in this document. Suitable FAU framework-type zeolites are available, for example, from Zeolyst International (Conshohocken, PA) and Tosoh Corporation (Tokyo, Japan).

The FAU structure type zeolite can have a SiO2/AhO3 molar ratio in a range from 5 to 100 (for example, 5 to 80, 5 to 60, 5 to 30, 10 to 100, 10 to 80, 10 to 60 or 10 to 30).

Suitable sources of aluminum in addition to the FAU framework type zeolite include hydrated alumina and water soluble aluminum salts (eg aluminum nitrate). Suitable sources of silicon include colloidal silica, fumed silica, precipitated silica, alkali metal silicates, and tetraalkyl orthosilicates.

Examples of suitable Group 1 or Group 2 (M) metals include sodium, potassium and calcium, with sodium being preferred. The metal (M) is generally present in the reaction mixture as the hydroxide.

The present framework-type zeolite AFX is synthesized using an organic structure directing agent comprising 1,3-bis(1-adamantyl)imidazolium cations (Q), represented by the following structure 1):

Suitable sources of Q are the hydroxides, chlorides, bromides and/or other salts of the quaternary ammonium compound. The reaction mixture also contains a source of hydroxide ions, for example, a Group 1 metal hydroxide such as sodium hydroxide or potassium hydroxide. The hydroxide may also be present as a counterion to the organic structure directing agent.

The reaction mixture may also contain seeds of a molecular sieve material, such as zeolite SSZ-16, from a previous synthesis, desirably in an amount of 0.01 to 10,000 ppm by weight (for example, 100 to 5000 ppm by weight). weight) of the reaction mixture.

For each embodiment described herein, the zeolite reaction mixture may be supplied by more than one source. Also, one source may provide two or more reaction components.

The reaction mixture can be prepared batchwise or continuously. The crystal size, morphology and crystallization time of the zeolite described herein may vary with the nature of the reaction mixture and the crystallization conditions.

Crystallization and post-synthesis treatment

Crystallization of the zeolite from the above reaction mixture can be carried out under static, drum or stirred conditions in a suitable reactor vessel, such as polypropylene bottles or Teflon-lined or stainless steel autoclaves. at a temperature of 125 °C. at 200 °C for a time sufficient for crystallization to occur at the temperature used, for example, 5 to 30 days. Crystallization is usually carried out under autogenous pressure.

Once the zeolite crystals have formed, the solid product is recovered from the reaction mixture by standard mechanical separation techniques, such as centrifugation or filtration. The crystals are washed with water and then dried to obtain the synthesized zeolite crystals. The drying step is typically carried out at a temperature of less than 200°C.

As a result of the crystallization process, the recovered crystalline zeolite product contains within its structure pore at least a portion of the organic structure directing agent used in the synthesis.

The zeolite as synthesized may be subjected to treatment to remove some or all of the organic structure directing agent used in its synthesis. This can conveniently be done by heat treatment (calcination) in which the synthesized material is heated to a temperature of at least about 370°C for at least 1 minute and generally no more than 20 hours. Heat treatment can be carried out at a temperature of up to 925 °C. Although subatmospheric pressure may be employed for the heat treatment, atmospheric pressure is desired for convenience. Additionally or alternatively, the organic structure directing agent can be removed by ozone treatment (see, eg, A.N. Parikh et al, Micropor. Mesopor. Mater. 2004, 76, 17-22). The organic-free product, especially in its metal, hydrogen, and ammonium forms, is particularly useful in the catalysis of certain organic (eg, hydrocarbon) conversion reactions. In the present disclosure, zeolite free of organic matter in its hydrogen form is referred to as the "active form" of the zeolite, with or without a metallic function present, such as Pt or Pd.

To the extent desired, the extra-framework Group 1 or 2 metal cations in the present framework-type zeolite AFX can be replaced according to methods well known in the art by ion exchange with other cations. Suitable substitutional cations include metal ions, hydrogen ions, precursor hydrogen ions (eg, ammonium ions), and combinations thereof. Preferred substitution cations are those that tailor catalytic activity for certain chemical conversion reactions.

Particularly preferred substitutional cations include hydrogen, rare earth metals, and metals from Groups 2 to 15 of the Periodic Table.

When used as a catalyst, it may be desirable to incorporate the present framework-type zeolite AFX with another material resistant to the temperatures and other conditions employed in chemical conversion processes. Such materials include active and inactive materials and synthetic or naturally occurring zeolites, as well as inorganic materials such as clays, silica and/or metal oxides such as alumina. The latter can be of natural origin or in the form of gelatinous precipitates or gels that include mixtures of silica and metal oxides. The use of a material together with the present AFX framework-type zeolite (i.e., combined with it or present during the synthesis of the new crystal), which is active, tends to change the conversion and/or selectivity of the catalyst in certain conversion processes. organic conversion. Inactive materials suitably serve as diluents to control the amount of conversion in a given process so that the products can be obtained in an orderly and economical manner without employing other means of controlling the rate of reaction. These materials can be incorporated into naturally occurring clays (eg bentonite and kaolin) to improve the crush strength of the catalyst under commercial operating conditions. These materials (ie clays, oxides, etc.) function as binders for the catalyst. It is desirable to provide a catalyst having good crush strength because in commercial use it is desirable to prevent the catalyst from breaking down into powdery materials. These clay and/or oxide binders have typically been used only for the purpose of improving the crush strength of the catalyst.

Natural clays that can be combined with the current AFX framework type zeolite include the montmorillonite and kaolin families, which families include the subbentonites, and kaolins commonly known as Dixie, McNamee, Georgia, and Florida clays or others in which the main constituent mineral is halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment or chemical modification. Useful binders for composition with the present framework-type zeolite AFX also include inorganic oxides, such as silica, zirconia, titania, magnesia, beryllium, alumina, and mixtures thereof.

In addition to the above materials, the present framework-type zeolite AFX can be compounded with a porous matrix material such as silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllium, silica-titania as well as compositions ternary such as silica-alumina-thorium, silica-alumina-zirconia, silica-alumina-magnesia and silicamagnesia-zirconia.

The relative proportions of the present framework-type zeolite AFX and the inorganic oxide matrix can vary widely, with the content of framework-type zeolite AFX ranging from 1 to 90 wt% (eg, 2 to 80 wt%). by weight) of the composite material.

Zeolite characterization

In its anhydrous and synthesized form, the present framework-type zeolite AFX has a chemical composition, in terms of molar ratios, as described in Table 2 below.

TABLE 2

wherein Q comprises 1,3-bis(1-adamantyl)imidazolium cations and M is a metal selected from Groups 1 and 2 of the Periodic Table.

In some embodiments, the present framework-type zeolite AFX has, in its anhydrous and synthesized form, a SiO2/AhO3 molar ratio in a range of greater than 50 to 90 (eg, >50 to 70, 52 to 90, 52 to 80, 52 to 70, 53 to 90, 53 to 80, 53 to 70, 55 to 90, 55 to 80, or 55 to 70).

It should be noted that the as-synthesized form of the present framework-type zeolite AFX may have molar ratios different from the molar ratios of the reactants of the reaction mixture used to prepare the as-synthesized form. This result may occur due to the incomplete incorporation of 100% of the reagents of the reaction mixture in the crystals formed (from the reaction mixture).

In its calcination, the present framework-type zeolite AFX has a chemical composition comprising the following molar ratio:

AI2O3 :(n)SiO2

where n has a value greater than 50 to 100 (for example, >50 to 90, >50 to 80, >50 to 70, 52 to 100, 52 to 90, 52 to 80, 52 to 70, 53 to 100 , 53 to 90, 53 to 80, 53 to 70, 55 to 100, 55 to 90, 55 to 80, or 55 to 70).

The present high silica AFX framework type zeolite is characterized by X-ray powder diffraction. Representative powder XRD patterns of AFX framework-type zeolites can be referenced in the "Collection of Simulated XRD Powder Patterns for Molecular Sieves," Fifth Revised Edition, Elsevier, 2007. Minor variations in the diffraction pattern may result from variations in the molar ratios of the framework species of the particular sample due to changes in the lattice constants. Also, sufficiently small crystals will affect the shape and intensity of the peaks, leading to significant peak broadening. Minor variations in the diffraction pattern may result from variations in the organic compound used in the preparation. Calcination can also cause minor changes in the X-ray diffraction pattern. Despite these minor perturbations, the basic crystal structure remains unchanged.

Using the methods described herein, it is possible to synthesize high silica AFX framework type zeolites substantially free of non-AFX material. The term "substantially free of non-AFX material" used herein means that the present AFX framework-type zeolite contains less than 5% by weight (eg, less than 2.5% by weight, less than 1% by weight). non-measurable weight or amount) of non-AFX material, as determined by conventional XRD techniques. Examples of such non-AFX materials include amorphous material, unreacted FAU framework type zeolite and CHA framework type zeolite. The non-AFX material may co-crystallize with the AFX material or mix with the AFX material.

Adsorption and Catalysis

The present framework-type zeolite AFX can be used as an adsorbent. For example, it can be used as a selective adsorbent to separate a first component (eg CO2) from a gas mixture comprising the first component and an additional second component (eg methane).

The present framework-type zeolite AFX can be used to catalyze a wide variety of chemical conversion processes, particularly organic compound (eg, hydrocarbon) conversion processes. Examples of chemical conversion processes that are effectively catalyzed by this material, alone or in combination with one or more other catalytically active substances including other crystalline catalysts, include those that require an acid-active catalyst.

The present framework-type zeolite AFX may be suitable for use as a catalyst in the conversion of oxygenates to one or more olefins, particularly ethylene and propylene. The term "oxygenates" is used herein to include aliphatic alcohols, ethers, carbonyl compounds (aldehydes, ketones, carboxylic acids, carbonates, and the like), and also heteroatom-containing compounds such as halides, mercaptans, sulfides, amines, and combinations from the same. The aliphatic moiety will normally contain from 1 to 10 carbon atoms (eg 1 to 4 carbon atoms).

Representative oxygenates include straight or branched chain lower aliphatic alcohols, their unsaturated counterparts, and their nitrogen, halogen, and sulfur analogs. Particularly suitable oxygenates are methanol, dimethyl ether, or combinations thereof, especially methanol. In the present oxygenate conversion process, a feedstock comprising an organic oxygenate, optionally with one or more diluents, is contacted in the vapor phase in a reaction zone with a catalyst comprising the present zeolite under process conditions. effective in producing the desired olefins. Alternatively, the process can be carried out in a liquid or mixed vapor/liquid phase. When the process is carried out in the liquid phase or in a mixed vapor/liquid phase, different feedstock conversion rates and selectivities may result. product depending on the catalyst and reaction conditions.

When present, the diluent(s) are generally non-reactive with the feedstock or zeolite catalyst composition and are typically used to reduce the concentration of the oxygenate in the feedstock. Suitable diluents include helium, argon, nitrogen, carbon monoxide, carbon dioxide, water, essentially unreactive paraffins (especially alkanes such as methane, ethane, and propane), essentially unreactive aromatic compounds, and mixtures thereof. Particularly suitable diluents are water and nitrogen, with water being especially preferred. Diluents may comprise from 1 to 99 mole % of the total feed mixture.

The temperature used in the oxygenate conversion process can vary over a wide range, such as 200°C to 1000°C (for example, 250°C to 800°C, 300°C to 650°C, or 400°C). at 600°C).

Light olefin products will form, although not necessarily in optimal amounts, over a wide range of pressures, including autogenous pressures and pressures in the range of 0.1 kPa to 10 MPa (for example, 7 kPa to 5 MPa, or 50 kPa to 1 MPa). The above pressures are exclusive of the diluent, if present, and refer to the partial pressure of the feedstock as it relates to oxygenates and/or mixtures thereof. High and low pressure extremes can adversely affect selectivity, conversion, coking rate, and/or reaction rate; however, light olefins such as ethylene can still be formed.

The process must be continued for a period of time sufficient to produce the desired olefin products. The reaction time can vary from tenths of a second to several hours. Reaction time is largely determined by reaction temperature, pressure, selected catalyst, weight hourly space velocity, phase (liquid or vapor), and design characteristics of the selected process.

A wide range of weight hourly space velocities (WHSV) for the feedstock will work in the present process. WHSV is defined as the weight of feed (excluding diluent) per hour per weight of a total reaction volume of zeolite catalyst (excluding inerts and/or fillers). The WHSV should generally be in the range of 0.01 to 500 hr-1 (eg, 0.5 to 300 hr-1, or 1 to 200 hr-1).

A practical embodiment of a reactor system for the oxygenates conversion process is a circulating fluidized bed reactor with continuous regeneration, similar to a modern fluid catalytic cracker. Fixed beds are generally not preferred for the process because the conversion of oxygenates to olefins is a highly exothermic process requiring multiple stages with heat exchangers or other cooling devices. The reaction also results in a high pressure drop due to the production of low pressure, low density gas.

The present framework-type zeolite AFX can be used in a catalytic process involving the conversion of at least one compound comprising at least one nitrogen-oxygen bond. Processes where the present zeolite is used as catalyst and/or catalyst support in a selective catalytic reduction (SCR) process are particularly suitable. In this process, a gaseous stream comprising nitrogen oxides (NOx) is selectively reduced in the presence of a reductant and a catalyst comprising the present framework-type zeolite AFX. Nitrogen oxides (mainly NO and NO2) are reduced to N2 while the reductant is oxidized. When ammonia is the reductant, N2 is also an oxidation product. Ideally, the only reaction products are water and N2, although some NH3 is usually oxidized with air to NO or N2O.

To promote catalytic activity, one or more transition metals can be incorporated into the zeolite support. Any suitable transition metal can be selected. Particularly effective transition metals for use during selective catalytic reduction include one or more of Cr, Mn, Fe, Co, Ce, Ni, Cu, Mo, Ru, Rh, Pd, Ag, Re, Ir, and Pt. In one embodiment, the transition metal is selected from Fe and Cu. In an exemplary embodiment, the transition metal is Cu. Any suitable and effective amount of transition metal can be used in the catalyst. The total amount of transition metal(s) that can be included in the zeolite can be from 0.01 to 10% by weight. % (eg, 0.5 to 5% by weight, or 1 to 2.5% by weight) based on the total weight of the zeolite support.

Zeolite catalyst for use in the reduction of nitrogen oxides may be coated onto a suitable substrate monolith or may be formed as extruded-type catalysts, but is preferably used in a catalyst coating. In one embodiment, the zeolite catalyst is coated onto a flow-through monolith substrate (i.e., a honeycomb monolith catalyst support structure with many small parallel channels running axially through the entire part) or monolith substrate. filter, such as a wall flow filter, etc. The zeolite catalyst for use herein may be coated (for example, as a wash coating component) onto a suitable monolithic substrate, such as a metal or ceramic flux monolithic substrate or a filter substrate, such as a filter. wall flow or partial or sintered metal filter

Alternatively, the zeolite may be synthesized directly on the substrate and/or may be formed on an extruded-type flow-through catalyst.

The gaseous stream comprising nitrogen oxides may contain one or more of NO, NO2 and N2O in addition to gases other than NOx such as N2, O2, CO, CO2, SO2, HCI and H2O. The gas stream may contain from 1 to 10,000 ppm (eg, 10 to 1,000 ppm or 50 to 500 ppm) NO.

Nitrogen oxides that are reduced using a catalyst containing the present framework-type zeolite AFX can be obtained by any process (eg, as a waste gas stream). In one embodiment, the NOx-containing gaseous stream is an exhaust gas from an internal combustion engine.

The reductant can be a nitrogen compound or a short chain hydrocarbon (C1 to Cs). Preferably, the reductant is a nitrogen compound. Suitable nitrogenous compounds include ammonia, hydrazine, and ammonia precursors (eg, urea, ammonium carbonate, ammonium carbamate, ammonium hydrogen carbonate, and ammonium formate). The gas stream comprising nitrogen oxides may contact the catalyst at a gas hourly space velocity of 5,000 to 500,000 h-1 (eg, 10,000 to 200,000 h-1).

The reduction of nitrogen oxides can be carried out at a temperature within the range of 100°C to 650°C (eg, 250°C to 600°C).

The reduction of nitrogen oxides can be carried out in the presence of oxygen or in the absence of oxygen.

examples

The following illustrative examples are intended to be non-limiting.

Example 1

Zeolite SSZ-16 was prepared according to the procedure described in US Patent No. 4,508,837. The silicon source was sodium silicate, the aluminum source was aluminum sulfate, and the structure directing agent was 1,4-di(1-azoniabicyclo[2.2.2]octane)butyl dibromide.

The XRD powder of the resulting product was characteristic of SSZ-16.

The product as synthesized had an SiO2/AhO3 molar ratio of 12, determined by ICP elemental analysis.

Comparative Example 2

Zeolite SSZ-16 was prepared according to the procedure described in US Patent No. 5,194,235. A PTFE cup was charged with 1.75 g of a sodium silicate solution, 0.18 g of zeolite LZ-210 (molar ratio NH4 -USY, SiO2/AI2O3= 15), 3.77 g of NaOH IN, 1.56 g deionized water and 0.49 g l,l'-(butane-1,4-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dibromide (DABCO-C4 dibromide -DABCO). The mixture was stirred with a spatula to homogenize. The final composition of the reaction mixture, in terms of molar proportions, was as follows:

The PTFE cup was stoppered and sealed in a stainless steel autoclave. The autoclave was then set on a rotary spit (43 rpm) inside a heated oven at 140 °C for 14 days. Solid products were recovered from the cooled reactor by filtration and washed with deionized water. The recovered solids were then allowed to dry in an oven overnight at 95°C.

The XRD powder of the resulting product was characteristic of SSZ-16.

The product as synthesized had a SiO2/AhO3 molar ratio of 9.5, determined by ICP elemental analysis.

Comparative Example 3

Example 2 was repeated except that the final composition of the reaction mixture, in terms of molar proportions, was as follows:

The powder XRD pattern of the resulting product was characteristic of SSZ-16.

The product as synthesized had an SIO2/Al2O3 molar ratio of 7.1, determined by ICP elemental analysis.

Comparative example 4

An AFX framework-type zeolite was prepared according to the procedure described in US Patent No.

8,562,942. A PTFE cup was charged with 0.19 g of CBVIOO Na-Y zeolite (Zeolyst International, molar ratio SiO2/Al2O3 = 5.1), 1 g of NaOH IN, 3.47 g of an aqueous solution of 1.3 -bis(1-adamantyl)imidazolium hydroxide (0.58 mmol OH/g solution) and 1.61 g of water. Next, 0.62 g of CAB-O-SIL® M-5 fumed silica (Cabot Corporation) was added. The mixture was stirred with a spatula to homogenize. The final composition of the reaction mixture, in terms of molar proportions, was as follows

The PTFE cup was stoppered and sealed in a stainless steel autoclave. The autoclave was then set on a rotary spit (43 rpm) inside a heated oven at 150 °C for 21 days. Solid products were recovered from the cooled reactor by filtration and washed with deionized water. The recovered solids were then allowed to dry in an oven overnight at 95°C.

The XRD powder of the resulting product was characteristic of AFX structure type materials.

The product as synthesized had an SiO2/AhO3 molar ratio of 28, determined by ICP elemental analysis.

Example 5

A PTFE cup was charged with 0.62 g CAB-O-SIL® M-5 fumed silica (Cabot Corporation), 0.18 g LZ-210 zeolite, 1.0 g NaOH IN, and 3.47 g of an aqueous solution of bis(1-adamantyl)imidazolium 1,3-hydroxide (0.58 mmol OH/g solution). The mixture was stirred with a spatula to homogenize. The final composition of the reaction mixture, in terms of molar proportions, was as follows:

The PTFE cup was stoppered and sealed in a stainless steel autoclave. The autoclave was then set on a rotary spit (43 rpm) inside a heated oven at 150 °C for 21 days. Solid products were recovered from the cooled reactor by filtration and washed with deionized water. The recovered solids were then allowed to dry in an oven overnight at 95°C.

The XRD powder of the resulting product was characteristic of AFX structure type materials.

The product as synthesized had a SiO2/AhO3 molar ratio of 66, determined by ICP elemental analysis.

Example 6

A PTFE cup was charged with 0.62 g CAB-O-SIL® M-5 fumed silica (Cabot Corporation), 0.25 g LZ-210 zeolite, 1.2 g NaOH IN, and 3.47 g of an aqueous solution of bis(1-adamantyl)imidazolium 1,3-hydroxide (0.58 mmol OH/g solution). The mixture was stirred with a spatula to homogenize. The final composition of the reaction mixture, in terms of molar proportions, was as follows:

The PTFE cup was stoppered and sealed in a stainless steel autoclave. The autoclave was then set on a rotary spit (43 rpm) inside a heated oven at 150 °C for 21 days. Solid products were recovered from the cooled reactor by filtration and washed with deionized water. The recovered solids were then allowed to dry in an oven overnight at 95°C.

The XRD powder of the resulting product was characteristic of AFX structure type materials.

The product as synthesized had an SIO2/AI2O3 molar ratio of 53, determined by ICP elemental analysis.

Claims (10)

1 . An AFX framework type zeolite having, in its calcined form, a composition comprising the molar ratio: AhO3:(n)SiO2 where n has a value of more than 50 to 100. 2 . The framework-type zeolite AFX according to claim 1, wherein n has a value of more than 50 to 80. 3 . The frame-type zeolite AFX according to claim 1, wherein n has a value of 52 to 70. 4 . An AFX framework type zeolite having, in its anhydrous, synthesized form, a composition, in terms of molar ratios, as follows:

wherein Q comprises 1,3-bis(1-adamantyl)imidazolium cations and M is a metal selected from Groups 1 and 2 of the Periodic Table. 5. The frame-type zeolite AFX according to claim 4, wherein the SiO2/AhO3 molar ratio is in a range of more than 50 to 80. 6. The frame-type zeolite AFX according to claim 4, wherein the SiO2/AhO3 molar ratio is in a range from 52 to 70. 7. A method for synthesizing the frame-type zeolite AFX according to claim 4, the method comprises: (a) providing a reaction mixture comprising: (1) an aluminum source comprising a FAU framework-type zeolite; (2) a separate source of silicon; (3) a source of at least one metal (M) selected from Groups 1 and 2 of the Periodic Table; (4) a 1,3-bis(1-adamantyl)imidazolium cation source (Q); (5) hydroxide ions; Y (6) water; Y (b) subjecting the reaction mixture to crystallization conditions sufficient to form frame-type zeolite crystals AFX, where the reaction mixture has a composition, in terms of molar proportions, as follows:

8. The method according to claim 7, wherein the crystallization conditions a temperature of 125 °C to 200 °C. 9. A process for converting a feedstock comprising an organic compound into a conversion product comprising the step of contacting the feedstock with a catalyst under organic compound conversion conditions, the catalyst comprising an active form of the framework-type zeolite AFX according to claim 1. 10. A process to selectively reduce nitrogen oxides (NO x), the process comprises contacting a gas stream containing NO x with a catalyst comprising the zeolite according to claim 1.